Link type anchor



A. H. GENTER LINK TYPE ANCHOR July 6, 1965 2 Sheets-Sheet 1 Filed May 1, 1963 INVENiOR.

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AABERTH. GEure fi/IS Arroeusv United States Patent LINK TYPE ANCHGR Albert H. Genter, Mount Lebanon, Pa. (769. Larchmont Road, Pittsburgh 16, Pa.) Flier! May 1, 1963, Ser. No. 277380 4 Claims. (Ci. 85-79) This application is a continuation in part of my copending applications, Serial No. 17,838, filed March 28, 1960, and Serial No. 147,643, filed October 25, 1961, both of which are now abandoned.

This invention relates generally to mine roof bolt anchors to replace heavy roof supporting timbers and more particularly to a specific roof bolt with anchor links of specific configurations.

The principal object of this invention is the provision of a mine roof bolt having as an anchor a simple link which is rigid and non-deformable by the anchor bolt and when the nut draws the bolt upwardly against plate embracing the roof, the ends of the link are forced laterally into the rock strata and form a diagonal bridge- This invention employs the simplest form of elements to produce an entirely new and novel result. First, the bolt is a simple bolt, five-eighths of an inch or better, having two nuts. The bottom or innermost nut functions as a shoulder and the top or outermost nut in cooperation with this shoulder functions to exert pressure on opposite ends of the link diagonally disposed on the bolt to laterally expelthe link into the adjacent strata. of rock. The link will lie with its opposite ends engaging the bolt so that it may ente the hole which may be one and one quarter inches in diameter for the five-eighths of an inch bolt and may be held by rubber bands; A fixed shoulder may be substituted for the inner nut but the rounded ends of the two nuts in opposed relation are more helpful in laterally expelling the link.

When the link lies in this manner diagonally on the bolt and the bolt is turned the ends of the link engaging the two nuts on opposite sides of the bolt force the opposite ends of the link outwardly in opposite directions. This is due to the fact that the threads are merely inthe link ends have penetrated the rockstructure clined planes and the nut faces cannot function as true parallel surfaces. Thread play increases this tendency of laterally expelling the opposite ends of the link as the nuts tilt due to their engagement with the link.

This mine roof anchor bolt is simple and is new'inthe field yet expansion anchor mine roof bolts are over thirty years old.

The links are also of simple construction in that they may be similar to a chain link. However, the rectangular cross section has been selected as the better structure of this application because the ends of the link have a biting edge to help in penetrating the adjacent strata of rock.

A further improvement in the anchor link is to bend its opposite ends laterally at right angles to its intermediate portion. This permits the ends of the link to out directly into and between the clevagesof the stone or strata. The

rounded ends of the nuts cooperate with the arcuate bend in the link ends to provide a greater lateral component force when the ends of the link initially penetrate the walls of the hole in the earth. The right angle ends on the links provide a bite that is in the direction of the .roof.

Patented July 6, 1965 projecting ends of the link. The link has a tendency to travel from the diagonal position in the hole to a position where the link becomes disposed at an increasingly greate angle to the-axis of the bolt. This places the straight intermediate portion of the link at an angle that induces greater lateral-forces on the link ends to produce better penetration or to pack the penetrated rock tighter V and provide a better anchor support fo the bolt.

The third and last form of this simple link is to provide link ends bent substantially at forty five degrees from the straight intermediate portion. This provides improved initial lateral forces by the rounded surface on the end of the nut against the sloping link ends which induces the greatest lateral forces on the link ends to initially penetrate the rock strata from the bolt hole. That is greater thaneither of the other two link forms. This forty-five degree angle on the ends sacrifices the initial disposition of the link on the bolt as against the link with opposite ends at right angles to the shank of the hole but is superior to the fiat straight link with no curved ends. However, the link with forty-five degree angle on'the'ends fits adequately against'the shank of the bolt to permit easy insertion in a'hole and is improved over the link with right angle ends in that the ends of this link are easily forced from betweenthe nut and shoulder to penetrate the adjacent rock strata of the mine Here the compromise is superior for penetration because of the presented angle of engagement between the rounded nut end and the arcuate surface in the fortyfive degree end of the link must engage to create the lateral penetrating forces. There is substantially no loss in the efiiciency of this link as its angle to the vertical or axis of the bolt increases as the initial disposition of the link surfaces is on approximately a forty-five degree angle and the links are substantially the same insofar as their intermediate straight portions and function the same when from the bolt hole. s p

Another object of this invention is the provision of a mine roof bolt anchor link having its opposite ends curved outwardly in opposite directions, irrespective of the angle, the intermediate straight portion of the links and the curved link ends extending in parallel transverse planes in opposite directions from the roof bolt on which the anchor link is mounted. -Such an anchor link'may be held to the bolt by'two small rubber bands. These rubber bandsmerely retain the link close against the bolt until the bolt is turned and the distance between the nut and shoulder is lessened. Inthis position the link is not much greater inexternal dimension than the nut, thus the unit is compact until it is inserted in position with the bolt head tight-againstthe roofplate and the bolt is turned.

link. As the bolt isturnedthe nut feeds down its rounded portionsforcing the link ends to slide ofi laterally and away from the nut and the shoulder and into engagement with the strata in the bolt holeiin'which the anchor is inserted. These transverse link ends are forced outwardly into the strata rather than merely wedge the bolt and link inthe hole. The link ends readily penetrate the strata in the hole inthe strata" to provide ,an anchor that supports a plate against the roof of the mine. A good penetration rather than wedging action is necessary under the circumstances since the roof bolts help support tons and tons of rock making up the roof of the mine.

A' small abutment or bead may be welded on the nut to insure that the nut stops against the link when the bolt is turned. Usually, however, the bend in the link forming the transverse link ends and the corners of the angular side wrench faces of the nut are sufficient to arrest the movement of the nut on the turning bolt.

The improved advancement of this roof bolt and these links not only simplifies the packing and handling but the opposite and transverse ends of the links provide a faster and more improved lock or anchor than that of the expansion or bulging type of anchoring device or that of the mere wedging type of anchoring device.

Other objects and advantages appear in the following description and claims.

The accompanying drawings show for the purpose of exemplification without limiting the claims thereto, certain practical embodiments of the invention wherein:

FIG. 1 is a view in side elevation showing an unexpanded anchor bolt and link of this invention in a hole in section.

FIG. 2 is a view in front elevation showing an unexpended anchor bolt and link of this invention in a hole in section.

FIG. 3 is a view in side elevation showing an expanded anchor bolt and link of this invention expanded in a hole shown in section.

FIG. 4 is a view in perspective showing the link alone.

FIG. 5 is a view in side elevation showing an unexpanded flat anchor link in the section of a hole employing a nut as a shoulder.

FIG. 6 is a view in side elevation showing an expanded flat anchor link in the section of a hole employing a fixed shoulder on the bolt.

FIG. 7 is a view in perspective showing a modification of the flat link shown in FIGS. 5 and 6.

FIG. 8 is a view in side elevation showing an unexpanded anchor link having its ends twisted outwardly to a 45 angle in a roof bolt hole shown in section.

FIG. 9 is a view in sideelevation showing an expanded anchor link having its ends twisted outwardly to a 45 angle in a roof bolt hole shown in section.

FIG. 10 is a view in perspective showingthe links of FIGS. 8 and 9.

Referring to the drawings the link bolt has an integral head 2 and the stem 3 is made sufi'iciently long to enable'the anchor to be placed in the hole 4 drilled upwardly into the ceiling of the mine a sufiicient distance to place the anchor link 5 in a solid or firm strata of the earth.

The stem 3 of the bolt 1 passes upwardly through the hole 6 of the plate 7. This plate is larger than the hole 4 and embraces the ceiling for a considerable area around the hole 4.

A nut 10 is run over the thread section 11 of the stem 3 to the end thereof and is employed as a shoulder that forms a lower abutment.

The upper nut 12 is placedon the threaded section 11 after the link 5 is slipped thereover. Two rubber bands 13 hold the link 5 close to the threaded portion 11 of the stem 3 when the nuts 10 and 12 are spaced further apart than the length of the link 5.

With the plate and the nuts and link mounted on the bolt, this assembly is ready for useand can take any abuse that tools of this kind get in a mine without harming or otherwise endangering the use or operation of this anchor bolt.

The link 5 consists of parallel sides 14 and 15 which terminate in transverse link ends l' and 17. These link ends have an arcuate section 18 that embraces the opposite sides of the threaded section 11 of the bolt stem 3. These linkends lie in parallel planes and are oppositely disposed from each other. Their outer ends are flattened as indicated at 20 and the material of the link is bent and twisted so as to form the round arcuate curves 21 where they join the opposite ends of the side members 14 and 15. The flat of the nut 12 engages in the rounded part 21 which causes the nut to be arrested when the bolt is turned. To insure the arresting movement of the nut 12 a welded bead 22 is placed at one corner of the nut 12 and as the bolt is rotated this bead engages in the rounded portion 21 of the link end 17 and holds the nut stationary while the bolt screws upwardly therethrough to set the link. Thus the bead 22 as well as the corners of the nut 12 aid in interlocking the nut with the rounded portion 21 of the link 5. The further the bolt is turned the closer the nut 12 approaches the nut or shoulder 19 and the further that the link 5 is pushed from the opposite sides of the threaded section 11 of the bolt stem 3 causing the link ends 16 and 17 to penetrate themselves into the earth forming the hole 4 thereby providing an anchor. The closer the nut 12 is brought down the threaded stem 11 to the nut 10, the more slanted the anchor link 5 becomes in the hole 4 and the further that it penetrates in the walls of the hole in properly anchoring this roof bolt. At this time the head 2 of the bolt is tightly against the plate 7 and thus supports the plate as shown in FIG. 3 and the ceiling or side wall engaged by the plate. When the bolt becomes so tight that it can no longer squeeze the link and force the ends in opposite directions outwardly into the hole 4 a suflicient anchoring force is obtained to lend support through the plate 7 to the ceiling surface.

As shown in FIGS. 5 and 6 the link 23 is fiat lying in a single plane. However, it has the same cross section and is preferably provided with the fiat ends 20 connected by the diagonal sections 24. As previously stated the cross sectional area of the link is substantially uniform throughout its complete circular section. As shown in FIG. 5 the link may be unable to fit as closely to the bolt as the link in the other views owing to the fact that the link is flat. However, the diagonally opposite edges of the end faces 24 in the link 23 resting on the shoulder 10 and under the movable nut 12 will be unable to stay in this position when the bolt head is turned. As the nut 12 is screwed down and the head 2 of the bolt 3 is rotated, the pressure exerted on the opposite diagonal edges of the link force the link laterally outwardly in both directions. The link first is forced from the area between the two opposed faces of the shoulder 10 and the nut 12 and the nut 12 continues to rest on top of the link when it is in the diagonal position as illustrated in FIG. 6. Continued rotation of the head 2 of the bolt will cause the nut 12 to work down the threaded section of the bolt until the plate 7 is tight against the under section of the roof. The plates 7 are, of course, of different sizes depending upon the character of the roof. Some roofs require quite a large plate; whereas other roofs need only a small plate. In any event, the welded head 22 will readily engage the upper surface of the link and hold the nut still to allow the bolt to ride upwardly therethrough until extreme pressure is brought to bear upon the link tending to orient the link to the horizontal position. This may never be achieved. However, the link may reside at an angle of from forty-five degrees to sixty degrees from the vertical axis of the bolt. 7

As shown in FIG. 6 the shoulder 10 has been replaced by a shoulder 25 which in fact is an integral portion of the bolt and in place of the bolt head 2 we have provided a nut 26 which is larger in diameter than the other nuts and the bolt heads owing to the fact that the shoulder 25 is substantially as large as the face of the shoulder 10 and is preferably likewise round as indicated in the drawings. Thus the hole 6 in the plate 7 as shown in FIG. 6 must be sufliciently large to admit the stem 27 of the bolt. The nut 26 is turned down on the threaded section 28 of the bolt until it bottoms on the threads and then this member becomes the actual bolt head. If it is desired to remove this anchor bolt, one need only to drill a hole upwardly between the threads of the nut 26 in the threaded bolt section 28 and drive the pin therein to make them integral.

Referring now to FIG. 7 a modified form of the link 23 is shown wherein this fiat link 36 is provided with the angular corners 24 and the flat ends 20. However, the inner wall of the link on the ends 16 and 17 may be cut away as by grinding at an angle that is conducive to allow the link 30 to lie closer to the bolt and within the outline of the opposed shoulders 'and 12. This cut away portion may be diagonally ground as indicated at 31 at opposite ends of the link. Thus we see that a fiat link can function as an anchor bolt, yet it is asimplecontinuous link incapable of being deformed by the pressure exerted by the nut on the bolt to express the link laterally and into the rock.

In the structure shown in FIGS. 8 and 9 the ends of the link 35 are bent outwardly in opposite directions but at an angle substantially forty-five degrees to the intermediate section of each link. This provides a nice even bend from the edge of the flat end 20 around the end of the link 17 and onwardly to the flat section 35 between the two bends which is substantially straight.

As soon as this link moves to the edge of either abutment face 10 or 12 the rounded portion of the nut 12 bears against the outermost surface of the link as indicated at 36 which is disposed at its relatively steep angle and which surface extends until the bend section 37 and thence at the end of the bend the link remains flat and straight between the two bends as indicated at 38.

Thus when the rounded portion of the abutments engage the surfaces 36 they are substantially at forty-five degree angles relative to the axis of the bolt which permits maximum lateral stresses to be directed by the abutment in the form of the nut 12 as it lowers on the surface 36 and can transmit more force laterally than any of the other link forms until they have reached such an angle. It is believed that this form of link is superior to the other two in View of this factor. However, the other two forms of the link will function. The transition of the rounded section 37 to the fiat section 38 likewise occurs at the proper time with the rounded section of the abutment faces 10 and 12 so as to express greater force on the link to permit it to penetrate the rock and anchor itself so as to provide a good roof support.

Although the link shown in FIGS. 1 and 4 lies closer to the bolt, the links of FIGS. 7 and 4 will likewise lie substantially as close which is conducive to a better assurance of forming an anchor.

As the bolt head 2 is turned as illustrated in FIG. 3 the nut abutment 12 lowers on the threaded section 11 of the bolt and forces the link laterally outwardly until the anchor is complete.

It is noted that the link is not supposed to Wedge in a hole as taught by the prior art. The link is caused to be moved laterally outwardly by forces causing the ends of the link to penetrate the strata;

This simple link, regardless of whether the ends are bent laterally outwardly in opposite directions or not, functions as a penetrating member in the strata of rock and thereby provides a support in itself for the abutment nut 12 to hold the plate 7 tightly against the roof of the mine and in this manner prevent new or further fractures in the rock causing the roof to fall. It is well known that when tunnels or mines are dug in the earth the air oxidizes the coal and the stone and all of the exposed earth structure, which has a tendency to rapidly decay the same. This decay is effective in the roof bolt holes as well as on the surface of the mine walls and, of course, the decay has a tendency to crumble away and allow a wedge type anchor to release wherein the simple link structure of this invention functions to penetrate the strata of rock in the bolt hole laterally in opposite directions so as to provide an entirely different type of anchor than that provided in the prior art.

It will be seen that the link being very loose on the bolt threads 11 is permitted freedom within the bolt hole 4 and it may move with the bolt hole until the ends 20 engage or otherwise penetrate and make an initial contact on the sides of the hole. In other words the link itself functions in aiding its initial penetration into the strata at opposite sides of the hole and making this initial con- 6 tact with the sides of thehole prevents the nut 12 from turning with the bolt 1. If it were not for the opposed abutments initially expressing the link laterally outwardly in opposite directions and later guiding and exerting pressure on the link to further this penetration, this type of transverse anchor could not be formed. Thus the opposed shoulders 10 or 25 and 12 are absolutely necessary in cooperation with the simple link structure with the ends of the linkinitially penetrating the sides of the hole for not only initially starting the anchoring'process, but also completing the anchoring process of the link.

In FIGS. 5 and 8 the links 23 and 35 shown therein are not retracted tightly against their respective bolts as the dotted inner surface of these links are not engaging the bolts. Thus these links may be laid closer along the bolts to enable them to enter a smaller hole if the nuts 12 were unscrewed further than that shown.

I claim:

1. A mine roof bolt assembly to be anchored in a drilled hole penetrating an upper rock strata from the roof of a mine, the lower strata loose due to mining, consisting of r a roof bolt plate to embrace the mine roof around the drilled hole and having a bolt hole therethrough,

a roof bolt to extend through said bolt hole to clamp said roof bolt plate against the roof and hold the rock strata in place,

a threaded section on the upper end of said bolt,

a nut threadably operable on the upper end of said bolt section,

an abutment in the form of a bead on the bottom of said nut,

means defining a non-movable shoulder adjacent the lower end of said threaded bolt section,

a non-deformable link consisting of an intermediate portion and opposite ends which are bent in opposite directions in parallel planes and at an angle lateral of the intermediate portion of said link,

an opening throughthe intermediate portion of said link to permit free movement and diagonal positioning of said link on said roof bolt,

said free movement of said link limited by said nut and said shoulder means to prevent said link from escaping over the same,

said nut and said shoulder forming substantially parallel pressure applying opposed abutment faces and spaced apart sufliciently to permit said link to lie substantially diagonally with respect to said bolt and said opposed abutment faces in order to enter and slide up into said drilled hole in the mine roof,

said opposite ends of said diagonally positioned link upon insertion of the roof bolt assembly into said drilled hole have sufficient contact with the sides of the drilled hole in order to frictionally engage the surface and permit the abutment on said nut to cooperate with the opening in said link to hold said nut while said bolt is turned to draw said nut toward said shoulder,

said opposed abutment faces expelling the opposite ends of said diagonal link laterally causing the link ends to penetrate the sides of the drilled hole to form a bridge anchor from which said nut and bolt draw said plate tightly against the mine roof to support the lower strata from the upper strata.

2. The mine roof bolt of claim 1 in that said opposite ends of said link are bent substantially ninety degrees from the intermediate portion of said link.

3. The mine roof bolt of claim 1 in that said opposite ends of said link are bent substantially forty-five degrees from the intermediate portion of said link.

4. A mine roof bolt assembly to be anchored in a drilled hole penetrating an upper rock strata from the roof of a mine, the lower. strata loose due to mining, consisting of a roof bolt plate to embrace the mine roof around the a roof bolt to extend through said bolt hole to clamp drilled hole and having a bolt hole therethrough,

said roof bolt plate against the roof and hold lower rock strata in place,

a threaded section on the upper end of said bolt,

shoulder means adjacent the lower end of said threaded bolt section,

a nut threadably operable on the upper end of said bolt section and having an abutment in the form of a bead extending downwardly toward said shoulder means,

a non-deformable link of substantially uniform cross section and of elongated configuration consisting of an intermediate portion and opposite ends which are bent in opposite directions in parallel planes and at an angle of forty-five degrees with respect to the intermediate portion of said link,

an opening through said intermediate portion of said link with down'ivar dly opposed rounded end portions and having an elongated configuration similar to said link to permit free movement and diagonal positioning of said link on said roof bolt,

said opening narrow enough to prevent escaping of said link over said nut and shoulder means,

characterized by the cooperative initial frictional engagement of said the opposite ends of said link with the sides of the drilled hole upon insertion of the roof bolt assembly into said drilled hole in combination with the cooperative interlocking of said abutment of said not with said rounded end portions of said link,

said cooperative combination to hold said nut secure while 'said bolt is turned to draw said nut toward said shoulder means expelling the opposite ends of said link laterally causing said ends to penetrate the sides of the drilled hole to form a bridge anchor from which said nut and bolt draw said roof bolt plate tightly against the mine roof to support the lower strata from the upper strata.

References (Jited by the Examiner UNITED STATES PATENTS 1,901,391 3/33 Forberg 853 2,177,138 10/39 Hollander -5 2,918,840 12/59 Roesler --79 2,933,969 4/60 Huyssen 85-3 FOREIGN PATENTS 4,779 2/97 Great Britain.

EDWARD C. ALLEN, Primary Examiner. 

1. A MINE ROOF BOLT ASSEMBLY TO BE ANCHORED IN A DRILLED HOLE PENETRATING AN UPPER ROCK STRATE FROM THE ROOF OF A MINE, THE LOWER STRATE LOOSE DUE TO MINING, CONSISTING OF A ROOF BOLT PLATE TO EMBRACE THE MINE ROOF AROUND THE DRILLED HOLE AND HAVING A BOLT HOLE THERETHROUGH, A ROOF BOLT TO EXTEND THROUGH SAID BOLT HOLE TO CLAMP SAID ROOF BOLT PLATE AGAINST THE ROOF AND HOLD THE ROCK STRATA IN PLACE, A THREADED SECTION ON THE UPPER END OF SAID BOLT, A NUT THREADABLY OPERABLE IN THE UPPER END OF SAID BOLT SECTION, AN ABUTMENT IN THE FORM OF A BEAD ON THE BOTTOM OF SAID NUT, MEANS DEFINING A NON-MOVABLE SHOULDER ADJACENT THE LOWER END OF SAID THREADED BOLT SECTION, A NON-DEFORMABLE LINK CONSISTING OF AN INTERMEDIATE PORTION AND OPPOSITE ENDS WHICH ARE BENT IN OPPOSITE DIRECTIONS IN PARALLEL PLANES AND AT AN ANGLE LATERAL OF THE INTERMEDIATE PORTION OF SAID LINK, AN OPENING THROUGH THE INTERMEDIATE PORTION OF SAID LINK TO PERMIT FREE MOVEMENT AND DIAGONAL POSITIONING OF SAID LINK ON SAID ROOF BOLT, SAID FREE MOVEMENT OF SAID LINK LIMITED BY SAID NUT AND SAID SHOULDER MEANS TO PREVENT SAID LINK FROM ESCAPING OVER THE SAME, 